Maybe it’s a take off on ink jet printer software. The air being the medium to “print” on, and the speed of medium pass through is equal to the acceleration of the water drops in free fall.
Then again, I could just be full of it. LOL!
That was my first thought as well.
All the technology of a printer, although it’s an interesting question about the valves.
Close, but no cigar!
You are confusing speed (velocity) and acceleration which is in fate the rate of change of velocity. Velocity has units of length per unit time as in inches per second or miles per hour. Acceleration is measured in units of length per unit time squared as say feet per second per second. The acceleration due to gravity is about 32 feet per second per second.
The actual speed of the water jet exiting the spray bar is dependent on the orifice coefficient of the control valve and the pressure in the distribution pipe supplying the water. Simply put the higher the pressure the faster the water jet exits. Once free of the nozzle, the water continues to accelerate due to gravity which causes the distortion visible when the display paints a star shape and the tips stretch out on the lower portion of the star as they are moving faster then the top portion. It's also visible in the circle patterns as they turn into ellipses as they drop.
The control valves are no doubt controlled by electric solenoids and I would judge them to be similar to the injector solenoid valves used in most automotive fuel injection systems. FI injectors put out variable length pulses of gasoline at rates of 40 to 50 cycles per second in today's engines.
Regards,
GtG
PS I worked as a design engineer for a hydraulics manufacture and have about 40 years experience designing solenoid valves and servo valves.